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Publikationen - Molekulare Signalverarbeitung

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Wasternack, C.; Hause, B. Jasmonsäure – ein universelles Pflanzenhormon: Blütenduft, Abwehr, Entwicklung Biologie in unserer Zeit 44, 164 - 171, (2014) DOI: 10.1002/biuz.201410535

Jasmonsäure (JA) und ihre Metaboliten kommen in allen niederen und höheren Pflanzen vor. Sie sind universell wirksame, aus Lipiden gebildete Signalstoffe bei der Abwehr von biotischem und abiotischem Stress sowie in der pflanzlichen Entwicklung. Rezeptor und Komponenten von JA–Signalketten wurden identifiziert. In der Entwicklung von Blüten, Früchten, Samen, Trichomen oder in der Abwehr von Insekten und Pathogenen treten ähnliche JA-vermittelte Signalproteine auf, die eine Feinregulation der Prozesse erlauben und eine Verbindung (cross-talk) zu anderenPflanzenhormonen aufweisen.

Jayaweera, T.; Siriwardana, C.; Dharmasiri, S.; Quint, M.; Gray, W. M.; Dharmasiri, N. Alternative Splicing of Arabidopsis IBR5 Pre-mRNA Generates Two IBR5 Isoforms with Distinct and Overlapping Functions PLoS ONE 9, e102301, (2014) DOI: 10.1371/journal.pone.0102301

The INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5) gene encodes a dual specificity phosphatase that regulates plant auxinresponses. IBR5 has been predicted to generate two transcripts through alternative splicing, but alternative splicing of IBR5has not been confirmed experimentally. The previously characterized ibr5-1 null mutant exhibits many auxin related defectssuch as auxin insensitive primary root growth, defective vascular development, short stature and reduced lateral rootdevelopment. However, whether all these defects are caused by the lack of phosphatase activity is not clear. Here wedescribe two new auxin insensitive IBR5 alleles, ibr5-4, a catalytic site mutant, and ibr5-5, a splice site mutant.Characterization of these new mutants indicates that IBR5 is post-transcriptionally regulated to generate two transcripts,AT2G04550.1 and AT2G04550.3, and consequently two IBR5 isoforms, IBR5.1 and IBR5.3. The IBR5.1 isoform exhibitsphosphatase catalytic activity that is required for both proper degradation of Aux/IAA proteins and auxin-induced geneexpression. These two processes are independently regulated by IBR5.1. Comparison of new mutant alleles with ibr5-1indicates that all three mutant alleles share many phenotypes. However, each allele also confers distinct defects implicatingIBR5 isoform specific functions. Some of these functions are independent of IBR5.1 catalytic activity. Additionally, analysis ofthese new mutant alleles suggests that IBR5 may link ABP1 and SCFTIR1/AFBs auxin signaling pathways.

Ziegler, J.; Abel S. Analysis of amino acids by HPLC/electrospray negative ion tandem mass spectrometry using 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) derivatization Amino Acids 46, 2799-2808, (2014) DOI: 10.1007/s00726-014-1837-5

A new method for the determination of amino acids is presented. It combines established methods for the derivatization of primary and secondary amino groups with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) with the subsequent amino acid specific detection of the derivatives by LC–ESI–MS/MS using multiple reaction monitoring (MRM). The derivatization proceeds within 5 min, and the resulting amino acid derivatives can be rapidly purified from matrix by solid-phase extraction (SPE) on HR-X resin and separated by reversed-phase HPLC. The Fmoc derivatives yield several amino acid specific fragment ions which opened the possibility to select amino acid specific MRM transitions. The method was applied to all 20 proteinogenic amino acids, and the quantification was performedusing l-norvaline as standard. A limit of detection as low as 1 fmol/μl with a linear range of up to 125 pmol/μl could be obtained. Intraday and interday precisions were lower than10 % relative standard deviations for most of the amino acids. Quantification usingl-norvaline as internal standard gave very similar results compared to the quantificationusing deuterated amino acid as internal standards. Using this protocol, it was possible to record the amino acid profiles of only a single root from Arabidopsis thaliana seedlings and to compare it with the amino acid profiles of 20 dissected root meristems (200 μm).
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